Here we report the first fatality caused by H1N1 influenza virus infection with acute respiratory distress syndrome in Korea. A 55-year-old man presented at our emergency department with dyspnea, fever, diffuse myalgia and malaise. Bilateral lung air-space consolidation was detected on his initial chest radiograph combined with severe hypoxemia. He was supported by mechanical ventilation and treated with antibiotics. A nasopharyngeal aspirate was positive for influenza A rapid antigen and oseltamivir was started on day 3 of admission. The nasal swab sample was positive for influenza H1N1 virus by real-time reverse-transcriptase polymerase chain reaction. Despite aggressive treatment, he had refractory hypoxemia and uncontrolled septic shock. On day 5 of admission he went into cardiac arrest and expired.